Bottom portion of a golf club head for a putter



FIG. 1 is a plan view of a bottom portion of a golf club head for a putter showing my new design; and,

FIG. 2 is a perspective view thereof.

The broken line showing of the remainder of the golf club head for a putter and the unshown top and front of the putter form no part of the claimed design. 

The ornamental design for a bottom portion of a golf club head for a putter, as shown and described. 